The present invention relates to a press ram for use in a pelleting machine for making tablets, comprising a rod-shaped ram holder having at one end a head for engagement with cams and at its other end an axial bore, a ram insert having at one end a pressing portion shaped in conformity with the profile of a tablet and at another end a cylindrical shaft which is substantially matingly received in the bore of the ram holder, with a radial shoulder of the ram insert engaging the facing end of the ram holder, and means for releasably holding the ram insert within the ram holder.
Such press rams are used in rotary pelleting machines for making tablets of a great variety of materials and for a great variety of applications. A press die plate usually driven about a vertical axis includes a plurality of dies having associated therewith a pair of press rams rotating synchronously with the die plate. Actuation of the press rams is effected via cams and pressure rollers.
It has become known to make such press rams of two parts. They comprise a rod-shaped ram holder having at one end a head for engagement with the cams and pressure rollers and at the other end an axial bore. Furthermore, they comprise a ram insert having a shaft which fits into the bore and has a portion projecting from the ram holder and serving as a pressing portion of a shape in conformity with the shape of the die. It has become known to fix the ram insert by means of a bolt to the ram holder and to secure it by means of an obliquely extending fixing bolt. In such a construction the ram inserts in the machine cannot be changed. Furthermore, there is a certain risk of the bores for the fixing bolts being filled with the material to be compressed. As a result cleaning thereof is difficult.
Furthermore, it has become known to fix the shaft of the ram insert at the ram holder by means of a radial fitting pin. Also this type of fixing does not allow for simple exchange of the ram insert.
It is an object of the present invention to provide a press ram for use in a pelleting machine wherein the ram insert may be readily exchanged by the users.